The invention relates to flexible line trimmers and brush cutters and, more particularly, to an anti-wind/wrapping assembly that prevents trimmed debris from winding on a trimmer.
One of the most irritating experiences when cutting into higher or taller vegetation with a common flexible line trimmer or brush cutter is the wrapping of long strands of vegetation around the axis of rotation of the rotating head. It also applies to vines, or previously cut vegetation lying on the ground. Additionally, it is not uncommon to run into invisible monofilament fishing line, often left along lake banks and streams that rapidly and very effectively snarls a trimmer head into a stalled rotation. As these strands become entangled within the trimmer head's openings and crevices, the debris winds with rotation, and accumulates into a massive bundle to then fill the open volume, and to reach adjacent stationary structure of the trimmer body. The wrappings rapidly bind and stall the rotating head from turning. During the binding process, unless the operator fails to shut down the rotation by releasing the trigger, heat builds up on the rotating or even the stationary parts to cause melting and structural damage to the components, thus often destroying the system.
When severed at their base, long vegetation cuttings (strands) drop onto the rotating parts below, and then are carried along with the rotation. They wind into a bundle under power, like a bobbin winds thread onto a spool. There are numerous scenarios regarding how the debris can be presented to the trimmer head areas. One end of the long debris pinches or binds onto the rotating shaft, or its direct attachment, which is under power from the driving motor. The continued powering and tightening of the strands forcefully wind and wrap the debris around and/or between each other to accumulate, and to become tighter and tighter. The accumulating snarl continues to rotate until it hits an obstruction (the connecting housings and components in the area) to then bind the entire system from turning.
The degree of bind can vary, but there will more likely be heavy vibration forces due to the imbalance of the wrapped mass to create further trimmer damage. Certainly, vibratory forces become risky to the operator who is trying to control the system which is now way out of balance. When combining the problematic imbalance with heat accumulation, it further results in more undesirable and destructive forces as well as melting damage to plastic or non-metallic components.
In all cases, the operator must inconveniently stop working by shutting down the trimmer to physically remove the compacted snarl of strands from the exposed rotating parts. FIG. 1 shows an exemplary trimmer with trimmed debris being wound into the space between the trimmer head and a gear box housing. FIGS. 2-4 show an exemplary trimmer including a glider disk, with trimmed debris being wound into the space between the trimmer head and the glider disk. Most times, the wrappings are so tightly compressed they cannot be removed by hand, nor can the snarl be removed even with needle-nose pliers. As a result of this locked and snarled system, the operator may use a sharp cutting knife to cut through the tightened snarl. Often it may be best to remove the bound debris from the trimmer with a full disassembly of the head components from the trimmer. This is a common nuisance and severe weakness of the trimmer or brush cutter.
As a preventive method (when possible), users are often advised to cut long and tall vegetation from the top down to achieve shorter segments that are less likely to wrap. This produces shorter strands that are less likely to wrap and accumulate.
While this hand-supported trimmer procedure may be helpful, it is counter to the purpose of a trimmer machine (especially with flexible line blade cutters) that may be ground supported, or more intended to cut lengthy or tall vegetation close to the ground. Therefore, while nuisance winding is a severe problem when it occurs above the head, there is an added need to prevent or reduce winding when using a ground supported trimmer glider system that utilizes a lower end ‘free-wheeling’ disc to be less vulnerable to the problems of accumulated windings that would likely occur above the head, or below the head (between the glider and the head). An exemplary glider system is described in copending U.S. patent application Ser. No. 14/280,916, the contents of which are hereby incorporated by reference.
Some trimmers may be equipped with a thin metal spacer plate compressed between the head and the upper geometry structure, which turns with the head under full power. While it may reduce the pinching gaps where the long debris can pinch, it remains under full power to wind fibrous debris into a tightly bound bundle. This plate is also part of a system design that reduces the ‘fill volume’ above the head where the snarled bundle would fill. Reducing the volume directly above the head and reducing the pinch points are beneficial, but only reduce some of the accumulation probability because once a strand begins to pinch, it will wind debris by the components under power into a tightened snarl.
The glider (a free-wheeling disc mounted below the head) enables a trimmer to be ground supported (below the cutting plane). It is also more susceptible to winding and wrapping as it promotes resting the trimmer on the ground to effectively ‘rotary mow’ with a flexible series of line blades. This new method of using a trimmer encourages cutting long and tall vegetation at the base and close to the ground. Therefore, the new method becomes even more vulnerable for debris to then drop down directly onto the rotating head and glider mechanisms to then wrap and bind at either the location above the head or below the head between the head and the glider. Therefore, a ground supported trimmer can be expected to have more exposure to wrapping potentials than a hand-supported trimmer. More likely, a handheld trimmer would not be cutting as low to the ground as frequently as would be a glider system.
While further analyzing the accumulation volume between the head and glider plate, there is a diminishing opening or pocket from outside in toward the center of the glider rotation. This volume is subject to the accumulation of dropping strands making it even more vulnerable to accumulate the undesirable debris.